Melanoma skin cancer starts in cells in the skin called melanocytes. Other names for melanoma skin cancer include malignant melanoma and cutaneous melanoma. Cutaneous means skin.
There are different types of melanoma. The different types are usually treated in the same way.
Types of melanoma
Superficial spreading melanoma
Superficial spreading melanoma tends to start growing outwards rather than downwards into the skin.
It's the most common type of melanoma. 60 to 70 out of every 100 people with melanoma (60% to 70%) have this type of melanoma. It’s most often diagnosed in people aged between 30 and 50 years.
It can develop anywhere on the body. But in men it's most common on the central part of the body (the trunk). And in women, it is most common on the legs.
Nodular melanoma tends to grow downwards into the deeper layer of the skin. They can grow quite quickly. There is often a raised area on the skin surface with this type of melanoma.
It's the second most common type of melanoma. Between 15 and 30 out of every 100 melanomas (between 15% and 30%) are this type. It's most often diagnosed in people in their 50's. It can develop in any part of the body.
Lentigo maligna melanoma
These melanomas develop from very slow growing coloured patches of skin called lentigo maligna or Hutchinson's melanotic freckle.
The lentigo maligna is flat and grows outwards in the surface layers of the skin. It might slowly get bigger over several years and might change shape or colour. If it becomes a lentigo maligna melanoma, it starts to grow down into the deeper layers of the skin and may form lumps (nodules).
Between 5 and 15 out of every 100 melanomas (5 to 15%) are this type. It's most common in people older than 60 years. They appear in areas of skin that get a lot of sun exposure, so are most common on the face. They are also more common in people who have spent a lot of time outdoors.
Amelanotic means without melanin. Melanin is a dark coloured pigment. So unlike other melanomas, amelanotic melanomas are usually red or skin coloured rather than dark coloured.
Other types of melanoma such as acral lentiginous can lack colour and are amelanotic melanomas.
This type of melanoma is rare. Around 8 out of every 100 melanomas (8%) are this type. They are often difficult to diagnose because of their lack of colour. They may be mistaken for other conditions of the skin.
Acral lentiginous melanoma
Acral lentiginous melanoma is usually found on the palms of the hands and soles of the feet or around the big toenail. It can also grow under the nails. It is much more common on the feet than on the hands.
This type is rare. 5 to 10 out of every 100 people diagnosed with melanoma (5 - 10%) have this type. But it is the most common type of melanoma in dark skinned people.
Other types of melanoma
Melanoma usually develops in the skin and is called cutaneous melanoma (cutaneous means skin). But rarely, it can start in the mucous membrane - this is the layer of tissue that covers the inside surface of parts of the body such as the mouth or vagina. This type of melanoma is called mucosal melanoma.
Possible places where mucosal melanoma can start include the:
- digestive system
Melanoma of the eye
Rarely, melanoma can start in the eye. It's sometimes called uveal melanoma or choroid melanoma.
Uveal melanoma starts in the uvea. The uvea is the middle layer of the eye and has 3 parts:
- iris (the coloured part)
- ciliary body
Most uveal melanomas develop in the choroid part of the uvea (choroid melanoma).
Desmoplastic melanoma is a rare type of melanoma. It can develop anywhere on your body but it’s most common in the head and neck area.
It's often the same colour as your skin and can look like a scar. This type of melanoma is more common in men than women.